Opinions about free software vs. federation vs. user experience aside, I don't think that this is a worthwhile or even realistic goal.  There are many people who are going to ask for support on IRC, and there are many who are willing to provide it there.  Therefore "support channels" on IRC will continue to exist in some form or fashion.  It seems fine to me that you would start one on Gitter or Slack - other folks seem to like those channels as well.

There might be a useful discussion buried in here about where official real-time _development_ discussion should go - but then, any weighty decisions should be discussed on the mailing list anyway to ensure that people from different time zones can see the discussion and participate in it asynchronously.

-glyph